Episode #206 Enhancing Safety During Anesthesia Care in the Prone Position

Hello and welcome back to the Anesthesia Patient Safety Podcast.  My name is Alli Bechtel, and I am your host. Thank you for joining us for another show. Our patient is still in the prone position under general anesthesia, and we are continuing the conversation from last week all about the underappreciated dangers of the prone position. This is an important time to remain vigilant since patients are at risk for positioning injuries as well as significant physiologic changes while in the prone position. We are going to do a review of the potential injuries and physiologic changes before offering practical considerations that you can use in your practice when positioning and managing patients in the prone position.

Before we dive into the episode today, we’d like to recognize Masimo, a major corporate supporter of APSF. Masimo has generously provided unrestricted support to further our vision that “no one shall be harmed by anesthesia care”. Thank you, Masimo – we wouldn’t be able to do all that we do without you!”

We are returning to the Article Between Issues, “The Underappreciated Dangers of the Prone Position” published on 30^th April 2024 and written by Taizoon Dhoon and colleagues. To follow along with us, head over to APSF.org and click on the Newsletter heading. The second one down is Articles Between Issues and from here scroll down until you get to our featured article today. I will include a link in the show notes as well.

Let’s start by reviewing potential injuries that may result from prone positioning.

• Direct pressure injuries
• Indirect pressure injuries due to decreased arterial blood flow and decreased venous drainage leading to ischemia or edema.
• Skin damage or blistering on the head and face or extremities from small body movements.
• Shoulder joint pain or even dislocation.
• Peripheral nerve injuries due to excessive stretching or direct pressure leading to microvascular compression.
• Postoperative vision loss
• Corneal abrasion and irritation
• Dependent edema, putting patients at risk for stroke, tongue swelling, tracheal compression, oropharyngeal and glottic edema. It is important to consider the safe and appropriate time for extubation to prevent a can’t ventilate, can’t intubate scenario.
• Hemodynamic instability and potential for cardiovascular collapse
• Postoperative pancreatitis and hepatic ischemia
• Increased venous bleeding.
• Postoperative thrombotic complications.
• Limb compartment syndrome, rhabdomyolysis, and the resultant renal failure.

And now, let’s review some of the physiologic changes that may occur in the prone position.

• Decreased intraocular perfusion from the combination of decreased venous outflow and increased intraocular pressure. Intraocular perfusion may be further reduced by increased intra-abdominal pressure, decreased preload, and decreased mean arterial pressure.
• Increased intracranial pressure combined with decreased cerebral blood flow leading to intracranial vessel distension.
• Increased hydrostatic pressure leading to dependent edema.
• Improvements in functional residual capacity, ventilation perfusion matching, and increased arterial oxygen tension.
• No changes in chest wall and lung compliance.
• Possible increases in intrathoracic pressure and peak airway pressures.
• Risk for increased pulmonary vascular resistance.
• Decreased cardiac index by about 25% from a decrease in stroke volume.
• Tachycardia and increased peripheral vascular resistance.
• Increased intrathoracic pressure combined with decreases in IVC filling, atrial compliance, and LV compliance leading to decreased cardiac output.
• Local compression of the anterior chest wall or abdomen leading to decreased right ventricular function or IVC preload.
• Abdominal compression leading to decreased arterial inflow and venous outflow to visceral organs.
• Increased intraabdominal venous compression.

Well, as you can see there are quite a few potential injuries and physiologic changes that anesthesia professionals need to be aware of when providing anesthesia care in a prone position. How can we keep our patients safe with all of these impending dangers? We are diving back into the article to review the clinical recommendations that the authors provide. We’ll break these down into the Preoperative, Intraoperative, and Postoperative phases. Here we go.

First up, let’s start with preoperative considerations. It is vital to complete a thorough and focused preoperative exam for all patients who will require prone positioning. Key components include patient history, airway examination, preexisting neurological deficits. This is a good time to discuss the anticipated duration of the procedure and proposed positioning. It is important to evaluate the patient’s capacity for prone positioning depending on co-morbidities and risk factors. Keep in mind that some patients with anatomical changes and movement restrictions that make positioning challenging may also have syndromes that predispose them to requiring procedures in the prone position including spine surgery or percutaneous nephrolithotripsy. The preoperative evaluation offers the ideal chance to attempt positioning in the desired position with the patient and this may even be done in an empty operating room before the day of surgery. For especially challenging positioning cases, after demonstrating that it is possible to safely obtain prone position, you may consider taking photographs and documenting important details or extra equipment that may be needed to achieve the position. The authors report that at their institution, positioning details for high-risk cases are documented in the preoperative record and images of the positioning specifics are included in the electronic medical record. If you are providing anesthesia care for prone procedures at your institution, you may want to consider these extra steps to help keep patients safe.

Another important consideration is preoperative cardiac evaluation using the perioperative assessment provided by the American College of Cardiology and the American Heart Association.

Here is a quick plug for the “2014 ACC/AHA Guideline on Perioperative Cardiovascular Evaluation and Management of Patients Undergoing Noncardiac Surgery. A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines” by Fleisher and colleagues. I will include the citation in the show notes as well. Head over to these guidelines and scroll down to section 4, “Approach to Perioperative Cardiac Testing.” In this section, there is a review about functional capacity and exercise capacity with the reminder that functional status can be used to help predict perioperative and long-term cardiac adverse events. Patients with good preoperative functional status are at lower risk for complications and patients who are not able to perform 4 METS, or metabolic equivalents, are at higher risk for complications. If we continue to read this section, the Duke Activity Status Index is included as Table 4. Below this, we get to a “Stepwise Approach to Perioperative Cardiac Assessment: Treatment Algorithm.” There are 7 steps to help guide your decision making. Keep in mind that for emergency surgery, you will need to perform a clinical risk stratification and proceed to surgery given the emergent nature of the surgery. Patients presenting with acute coronary syndrome will need to be evaluated by cardiology and treated prior to undergoing elective surgery. Continue through the rest of the steps of the algorithm to determine whether further testing is needed or if the patient may safely proceed to the operating room. And now, let’s return to the APSF article.

For patients who require further preoperative cardiac evaluation, stress echocardiography can help to determine the risk of ischemic heart disease as well as provide vital information about right ventricular function, pulmonary hypertension, and valvular heart disease. Given the significant physiologic changes that occur in the prone position, there should be a low threshold for preoperative echocardiography for high-risk patients or for those high-risk procedures such as complex spine surgery. Not all patients will be able to tolerate prone position and it may be necessary to modify with lateral or supine position if possible. For high-risk patients who must be positioned prone for the surgery or procedure, you may want to consider additional monitoring and access with central venous catheter, intra-arterial catheter, echocardiography with availability of inotropes, vasopressors, and pulmonary vasodilators.

It’s time to move into the operating room. Are you prepared for prone positioning? Here we go.

Prior to positioning prone, you will need to secure the endotracheal tube carefully in correct position. This may require some additional steps. Taping the tube may be suitable for a short procedure in the prone position, but consider using flat tracheostomy ties to secure the endotracheal tube. For surgeries on the head and neck when the tube cannot be tied in place, you may consider suturing the tube to a tooth or jaw or placing a nasal tube and securing it to the membranous nasal septum. While still in the supine position, consider any additional access or monitoring needs such as a central line or arterial line. When it is time to position, you will likely need about 5-6 team members including the anesthesia professional and the surgeon or proceduralist. It is important to maintain cervical inline stabilization with the head and neck in neutral position during positioning. Keep a close eye on the endotracheal tube to make sure that it is not dislodged during the surgery or any position changes especially if the head is secured with pins or a halo. You may want to secure the circuit to help prevent the weight of the circuit and gravity from dislodging the endotracheal tube. In addition, neck flexion may lead to main-stem positioning of the tube, so it is important to maintain neutral neck positioning and ensure equal and bilateral breath sounds after positioning.

Arm positioning depends on the type of procedure. Any movement of the arms should occur independently of the other arm to prevent shoulder joint injury especially during the initial prone positioning and during the re-positioning supine at the end of the case. Additional considerations include:

• Keeping the axilla free from tension
• Additional padding around the ulnar nerve
• Positioning arms slightly anterior to the shoulders in the coronal plane with the arms less than the patient’s full extension at the elbow joint to protect the brachial plexus and biceps tendon.

Once the patient is in the prone position, you have more work to do.

• First, check on the vital signs. Is the patient hemodynamically stable? Are your monitors working? The bed should remain in the room until hemodynamic stability is confirmed. For patients who become unstable once in the prone position, it is possible to quickly re-position supine and resuscitate, evaluate and treat the cause of the hemodynamic changes without delay.
• Next, make sure that appropriate padding is used to help keep your patient safe. Throughout the case, you will need to check pressure points as well as the eyes, mouth, and neck for proper positioning to help prevent any pressure-related injuries.

Okay, the case has been completed and the patient has been returned to the supine position. This is the time to evaluate for facial, lingual, and glottic edema, which may be minimized by keeping the head of the bed slightly elevated during the case. Patients with significant edema may need to remain intubated and monitored in the intensive care unit until the edema has resolved and it is safe to extubate. Patients who can be extubated at the end of the case may require higher level of care postoperatively in the intensive care unit depending on the patient’s comorbidities, the surgical procedure, and any significant hemodynamic changes.

Whew, we made it to the end of our prone position case and the article. The authors remind us that complications from the prone position are recognized, but often underestimated. There is a call to action for anesthesia professionals to understand the pattern of pressure-related injuries and physiologic changes that may occur during a procedure in the prone position and remain vigilant to help keep patients safe. This starts with the preoperative evaluation to determine if the patient can undergo a procedure in the prone position safely or if an alternative position is required. For high-risk patients, teamwork between the surgeon or proceduralist and the anesthesia professionals is essential in order to develop a strategy to help keep patients safe in the prone position.

If you have any questions or comments from today’s show, please email us at [email protected]. Please keep in mind that the information in this show is provided for informational purposes only and does not constitute medical or legal advice. We hope that you will visit APSF.org for detailed information and check out the show notes for links to all the topics we discussed today.

The APSF Newsletter is the official journal of the Anesthesia Patient Safety Foundation. Readers include anesthesia professionals, perioperative providers, key industry representatives, and risk managers. It is free of charge and available in a digital format with a focus on anesthesia-related perioperative patient safety issues. The June Newsletter has just been published, but the deadline for the October 2024 APSF Newsletter is right around the corner on July 10^th! Check out the guide for authors over at APSF.org for more information and I will include a link in the show notes as well. Who knows, you could be the next APSF Newsletter author and we might be featuring your article on a future Anesthesia Patient Safety Podcast! So, what are you waiting for, go ahead and submit your article today!

Until next time, stay vigilant so that no one shall be harmed by anesthesia care.

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